<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        * {
            margin: 0;
            padding: 0;
        }

        body {
            height: 9990px;
        }

        div.flag {
            position: fixed;
            top: 0;
            right: 0;
            bottom: 0;
            left: 0;
            width: 900px;
            height: 600px;
            margin: auto;
            background: red;
        }

        .x {
            position: absolute;
            width: 0;
            height: 0;
            border-top: none;
            border-left: 30px solid transparent;
            border-right: 30px solid transparent;
            border-bottom: 80px solid yellow;
        }

        .x::before {
            position: absolute;
            top: 65px;
            left: -100px;
            content: '';
            width: 0;
            height: 0;
            border-top: none;
            border-left: 100px solid transparent;
            border-right: 100px solid transparent;
            border-bottom: 70px solid yellow;
            transform: rotate(35deg);
        }

        .x::after {
            position: absolute;
            top: 65px;
            left: -100px;
            content: '';
            width: 0;
            height: 0;
            border-top: none;
            border-left: 100px solid transparent;
            border-right: 100px solid transparent;
            border-bottom: 70px solid yellow;
            transform: rotate(-35deg);
        }

        .x0 {
            transform: translate(120px, 55px) scale(0.88)
        }

        .x1 {
            transform: rotate(-50deg) translate(155px, 200px) scale(.3)
        }

        .x2 {
            transform: rotate(-25deg) translate(265px, 195px) scale(.3)
        }

        .x3 {
            transform: rotate(0deg) translate(330px, 150px) scale(.3)
        }

        .x4 {
            transform: rotate(20deg) translate(330px, 105px) scale(.3)
        }
    </style>
</head>

<body>
    <div class="flag">
        <div class="x x0"></div>
        <div class="x x1"></div>
        <div class="x x2"></div>
        <div class="x x3"></div>
        <div class="x x4"></div>
    </div>
</body>

</html>